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Icelandic volcano’s ash blanket was electric

THE volcanic ash cloud that has shrouded much of Europe in recent weeks had a positive electrical charge – a fact aircraft could have used to keep flying.

On 19 April, Giles Harrison at the University of Reading in the UK and colleagues used detectors aboard a weather balloon to measure the charge in the ash cloud over Scotland. It reached 0.5 picocoulombs per cubic metre in areas where there were 50 particles of ash per cubic centimetre of air (Environmental Research Letters, DOI&colon; 10.1088/1748-9326/5/2/024004). That’s around 1/20th of the danger level set by the UK Civil Aviation Authority. A similar detector on aircraft could alert …